Q.1 Which of the following elements has the highest electronegativity?
Fluorine
Oxygen
Chlorine
Nitrogen
Explanation - Fluorine has the highest electronegativity (3.98 on the Pauling scale) among all elements.
Correct answer is: Fluorine
Q.2 Which period contains elements with partially filled d-orbitals?
Period 1
Period 2
Period 4
Period 3
Explanation - Period 4 contains the first transition series where elements have partially filled d-orbitals.
Correct answer is: Period 4
Q.3 Which of the following elements is an alkali metal?
Calcium
Sodium
Aluminium
Sulfur
Explanation - Sodium belongs to Group 1 of the periodic table, which contains alkali metals.
Correct answer is: Sodium
Q.4 Ionization energy generally _____ across a period from left to right.
Decreases
Increases
Remains constant
Varies irregularly
Explanation - Ionization energy increases across a period due to increasing nuclear charge and decreasing atomic size.
Correct answer is: Increases
Q.5 Which element has the largest atomic radius?
Potassium
Calcium
Magnesium
Sodium
Explanation - Potassium has the largest atomic radius because atomic size increases down a group.
Correct answer is: Potassium
Q.6 Which group in the periodic table contains noble gases?
Group 1
Group 17
Group 18
Group 16
Explanation - Group 18 elements are noble gases, known for their inertness.
Correct answer is: Group 18
Q.7 Which of the following elements has the lowest electronegativity?
Cesium
Lithium
Potassium
Rubidium
Explanation - Cesium has the lowest electronegativity because it is the largest element in its group and easily loses its valence electron.
Correct answer is: Cesium
Q.8 Which of the following properties decreases down a group?
Atomic radius
Electronegativity
Metallic character
Number of shells
Explanation - Electronegativity decreases down a group because valence electrons are farther from the nucleus.
Correct answer is: Electronegativity
Q.9 Which element belongs to the halogens?
Bromine
Oxygen
Nitrogen
Sodium
Explanation - Bromine is in Group 17, known as halogens.
Correct answer is: Bromine
Q.10 Which of the following has the highest first ionization energy?
Sodium
Neon
Magnesium
Aluminium
Explanation - Neon is a noble gas with a stable octet, so it requires more energy to remove an electron.
Correct answer is: Neon
Q.11 Which of the following elements is a transition metal?
Iron
Calcium
Potassium
Chlorine
Explanation - Iron is a transition metal because it has a partially filled d-orbital.
Correct answer is: Iron
Q.12 What is the general trend of metallic character across a period?
Increases
Decreases
Remains constant
Varies irregularly
Explanation - Metallic character decreases across a period as elements become less likely to lose electrons.
Correct answer is: Decreases
Q.13 Which of these elements has the smallest atomic radius?
Boron
Carbon
Nitrogen
Fluorine
Explanation - Fluorine has the smallest atomic radius in this set due to high nuclear charge pulling electrons closer.
Correct answer is: Fluorine
Q.14 Which element is most likely to form a cation with a +2 charge?
Magnesium
Aluminium
Sodium
Chlorine
Explanation - Magnesium loses two electrons to achieve a stable noble gas configuration, forming Mg²⁺.
Correct answer is: Magnesium
Q.15 Which element is a metalloid?
Boron
Aluminium
Phosphorus
Sodium
Explanation - Boron exhibits both metallic and non-metallic properties, classifying it as a metalloid.
Correct answer is: Boron
Q.16 Which of the following elements is least reactive?
Sodium
Potassium
Neon
Calcium
Explanation - Neon is chemically inert because it is a noble gas with a stable electron configuration.
Correct answer is: Neon
Q.17 Which of the following shows a decrease in atomic radius across the period?
Li → Be → B → C → N → O → F
Na → Mg → Al → Si → P → S → Cl
Both A and B
None of the above
Explanation - Atomic radius decreases across a period in both cases due to increasing nuclear charge.
Correct answer is: Both A and B
Q.18 Which element has a completely filled d-subshell in its ground state?
Zinc
Copper
Iron
Chromium
Explanation - Zinc has a d¹⁰ configuration, so its d-subshell is completely filled.
Correct answer is: Zinc
Q.19 Which of these elements has the highest electron affinity?
Chlorine
Fluorine
Bromine
Iodine
Explanation - Chlorine has the highest electron affinity due to a smaller size and high nuclear charge, making it easier to gain an electron.
Correct answer is: Chlorine
Q.20 Which of the following trends increases down a group?
Electronegativity
Ionization energy
Atomic radius
Electron affinity
Explanation - Atomic radius increases down a group as new electron shells are added.
Correct answer is: Atomic radius
Q.21 Which element is placed in Group 16?
Oxygen
Nitrogen
Fluorine
Neon
Explanation - Oxygen is a chalcogen, placed in Group 16 of the periodic table.
Correct answer is: Oxygen
Q.22 Which element is a representative (main group) element?
Sodium
Iron
Copper
Zinc
Explanation - Sodium is in Group 1 and is a main group element.
Correct answer is: Sodium
Q.23 Which element is classified as a lanthanide?
Neodymium
Uranium
Lead
Thorium
Explanation - Neodymium is one of the 14 lanthanide elements, occupying the 4f block.
Correct answer is: Neodymium
Q.24 Which property is most closely related to the number of valence electrons?
Atomic radius
Ionization energy
Chemical reactivity
Metallic character
Explanation - Chemical reactivity is largely determined by the number of valence electrons an element has.
Correct answer is: Chemical reactivity
Q.25 Which element has a noble gas configuration in its ground state?
Argon
Sodium
Oxygen
Aluminium
Explanation - Argon has a complete octet in its valence shell, giving it a stable noble gas configuration.
Correct answer is: Argon